Currently, efforts in mobile telecommunications developments are directed to providing broadband data communications, known as 3.5G and 4G, using various competing radio access technologies (RATs) aiming to achieve high bandwidth combined with low latency, high efficiencies and flexibility. High Rate Packet Data (HRPD), also referred to as 1xEV-DO or High Data Rate (HDR), is a high-speed CDMA-based wireless data technology. WiMAX is an IEEE standard 802.16e for mobile technology. Long Term Evolution (LTE) is a Third Generation Partnership Project (3GPP) for enhancing UMTS. Ultra Mobile Broadband (UMB) is a 3GPP2 project.
A mobile terminal (MS) may have a capability for communicating with networks of different technology types. If conditions deteriorate, for example, when the mobile terminal is connected to a node in one network, it may be desirable to transfer it to a new connection, which may be another node of the same network or a node in a different network. Signaling messaging is required between the mobile terminal and elements of a potential new target network node so as to complete handover preparation, for example, by transferring information regarding the context of the mobile terminal, and to carry out handover from a source node to a target node once the necessary steps have been fulfilled. If handover involves transfer between networks of different technology types, some mechanism must be provided to permit signaling messaging for use in making a connection between the mobile terminal and the target node to be sent to the target network to establish communication between them.
One problem during inter-technology handover (HO) is timing for real-time services. It is desirable that the traffic interruption during such HO is kept within 300 ms to make the HO seamless and reduce the likelihood of real-time service being degraded.
Each Radio Access Technology (RAT) uses different protocols and architectures to establish an IP (Internet Protocol) service for an MS. Many of them involve the setup of the Radio Access Network session for the MS and the setup of L3 connectivity. For example: WiMax requires WiMax RAN access and WiMax session and IP session setup. HRPD requires HRPD session, PPP session and MIP session setup. Each one of these setups may take any time between 1-5 seconds. Therefore, the setup of these sessions and reservation of the resources must be done in a “make-before-break” fashion, that is, before the actual HO execution. This is achieved by “tunneling” of target technology messages over the current serving technology.
One possible tunneling mechanism is to rely directly on the IP network of the serving technology, which may be termed IP encapsulation, and tunnel the “pre-registration” directly from serving technology, via the Home Agent (HA), to the target technology's Radio Access Network (RAN).